This invention relates generally to robotic systems of the type which are employed in automation, and more particularly, to a robotic system which provides a measure of flexibility intermediate of cam-driven or linkage-based conventional mechanisms, which provide no flexibility, and serial robots which provide great flexibility, but at high cost.
There is a need to provide a robotic system which is useful in automation and achieves a reasonable measure of flexibility at relatively low cost. The term "flexibility" refers to the ability of a robotic system to be deployable to perform a variety of tasks. In this context, the term "task" refers to a mechanized motion in one, two, or three dimensional space along a prescribed path.
Hard automation systems, which include systems which operate in response to cam drives or linkage-based mechanisms, provide no flexibility. However, such systems provide significant operational advantages, such as high-speed applications, as well as good accuracy and repeatability. Serial robots, on the other hand, such as a six-axis industrial robot, can be recycled by simply reprogramming the robot to perform any one or more of a great variety of different tasks within it working envelope. Quite often, however, there is not a need for such great flexibility, although there is a need for some flexibility greater than that which is afforded by hard automation systems. In other words, there is a need for a semi-flexible automation system.
Serial industrial robots are widely employed in automated manufacturing operations, such as in the assembly of mechanical and electronic components, welding, painting, sealing, etc.. flexible manufacturing applications demand the use of such expensive robots. There are, however, many applications where serial six-axis robots are not often recycled from one task to another, and therefore there is a great expense associated with a flexibility which is not required. In addition, in certain automated environments where six-axis robots are employed, there is not a need for five or more degrees of freedom. Thus, there is a need for a system which can operate in the middle ground between serial robots and hard automation. Such an intermediate system should be reconfigurable with limited flexibility, yet achieve operational efficiency and cost-effectiveness.
The need for only limited flexibility arises from the fact that in most manufacturing environments, there will always be fundamental similarities between the different products on a given production line. Such similarities include, for example, overall size, overall weight, desired mechanical paths, etc. Consequently, there are present corresponding similarities in the robot workspace requirements, the paths traced by the end-effector, the accuracy and precision with which the task must be accomplished, and the operating speed. For example, it is not likely that computers and refrigerators would be manufactured on the same production line, even at different times. Yet, different models of computers or different models of refrigerators may be manufactured or assembled on a particular production line, and there would be only limited differences between the various models within each such product line.
It is, therefore, an object of this invention to provide an inexpensive robotic system which exhibits greater flexibility than conventional hard automation systems.
It is another object of this invention to provide a robotic mechanism which can achieve high-speed operation.
It is also an object of this invention to provide a light weight robotic mechanism.
It is a further object of this invention to provide an adjustable robotic mechanism which can achieve high accuracy and repeatability.
It is additionally an object of this invention to provide a robotic system which can perform tasks requiring motion having two or more dimensions of freedom while employing relatively few actuators and a simple control system.
It is a yet further object of this invention to provide a robotic system which can easily and inexpensively achieve continuous trajectories point-to-point.
It is also another object of this invention to provide a robotic system which is modular in its construction.
It is yet an additional object of this invention to provide a system for designing closed loop actuation mechanisms to achieve predeterminable motion of an end-effector.
It is still another object of this invention to provide a system for illustrating the effect of adjustability of design parameters on the shape of trajectories traced by an end-effector.